Skip to content

Emit null.asInstanceOf[T] as the initial value for synthetic vars. #8

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Closed
wants to merge 1 commit into from
Closed

Emit null.asInstanceOf[T] as the initial value for synthetic vars. #8

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
1 change: 1 addition & 0 deletions project/local.sbt
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1 @@
addSbtPlugin("com.github.mpeltonen" % "sbt-idea" % "1.3.0")
13 changes: 6 additions & 7 deletions src/main/scala/scala/async/TransformUtils.scala
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -27,6 +27,7 @@ private[async] final case class TransformUtils[C <: Context](c: C) {
val apply = newTermName("apply")
val applyOrElse = newTermName("applyOrElse")
val tr = newTermName("tr")
val asInstanceOf = newTermName("asInstanceOf")
val matchRes = "matchres"
val ifRes = "ifres"
val await = "await"
Expand All @@ -39,13 +40,11 @@ private[async] final case class TransformUtils[C <: Context](c: C) {
def fresh(name: String): String = if (name.toString.contains("$")) name else c.fresh("" + name + "$")
}

def defaultValue(tpe: Type): Literal = {
val defaultValue: Any =
if (tpe <:< definitions.BooleanTpe) false
else if (definitions.ScalaNumericValueClasses.exists(tpe <:< _.toType)) 0
else if (tpe <:< definitions.AnyValTpe) 0
else null
Literal(Constant(defaultValue))
def defaultValue(tpe: Type): Tree = {
Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

See https://github.com/scala/scala/blob/master/src/compiler/scala/tools/nsc/transform/patmat/MatchCodeGen.scala#L76 for another duplication site. Looking at it again, it should probably use mkCastPreservingAnnotations and move to TreeGen.

Copy link
Member Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

We're already downcasting to reflect.internal in few places to get at some of the goodness. We need to expose a bit more of this to the macro authoring public.

if (tpe <:< definitions.BooleanTpe) c.literalFalse.tree
else if (definitions.ScalaNumericValueClasses.exists(tpe <:< _.toType)) c.literal(0).tree
else if (tpe <:< definitions.AnyValTpe) c.literal(0).tree
else TypeApply(Select(c.literalNull.tree, name.asInstanceOf), List(TypeTree(tpe))) // Cast our way out of https://github.com/scala/async/issues/6
}

def isAwait(fun: Tree) =
Expand Down
36 changes: 36 additions & 0 deletions src/test/scala/scala/async/run/DefaultValueBugSpec.scala
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,36 @@
/*
* Copyright (C) 2012 Typesafe Inc. <http://www.typesafe.com>
*/

package scala.async
package run

import language.{reflectiveCalls, postfixOps}
import scala.concurrent.{Await, Future, ExecutionContext, future}
import scala.concurrent.duration._
import scala.async.Async.{async, await}
import scala.async.run.anf.State
import org.junit.Test
import org.junit.runner.RunWith
import org.junit.runners.JUnit4

@RunWith(classOf[JUnit4])
class DefaultValueBugSpec {

import ExecutionContext.Implicits.global

def m2[T](in: Any, f: Any => T, fut: Future[T]) = async {
in match {
case _ =>
await(fut)
}
}

@Test
def defaultValueForGenericTpe() {
val res = m2[Int]("in", _ => 1, async(2))
val value = Await.result(res, 2.seconds)
value mustBe (2)
}
}